When a semiconductor device works, it has to stay with a proper range of temperature to maintain good efficiency. For example, solar cells, light emitting diodes (LEDs) and thermoelectric semiconductor devices (e.g. thermoelectric generators) operating under high junction temperature will have reduced efficiency, or even color drift in the case of LEDs. For concentrating solar cells and high power LEDs, heat dissipation is particularly important. However, to such high power devices, a conventional metal fin heat sink is limited in capability of heat dissipation, and has high thermal resistance, while being bulky and heavy.
U.S. Pat. No. 4,211,581 immerses a light converter in a transparent liquid having a low boiling point, such that heat generated by the light converter will heat up the transparent liquid to vapor so as to remove the heat. However, air bubbles in the boiling liquid are likely to accumulate at the surface of the light converter and thus bar the liquid at the periphery from coming inside to contact the light converter. Consequently, the heat removal is hindered. Although the liquid also evaporates at the liquid surface, liquid convection has high thermal resistance, so the efficiency of its thermal transfer is poor, and therefore is weak in heat dissipation. In addition, the liquid surface of the transparent liquid adversely affects the light converter in terms of absorption for radiant energy and/or light.
U.S. Pat. No. 4,166,917 provides a concentrating solar receiver, in which a solar cell is such installed on support rings that pins connecting the support rings transfer the heat generated by the solar cell to an external heat pipe with a working fluid running therein to remove therefrom. Nevertheless, the heat pipe will significantly increase the volume and structural complexity of the solar receiver, being unfavorable to miniaturization of the apparatus.
U.S. Pat. No. 4,491,683 fills a chamber with gas so that when a cooling system disposed on the back side of a photoreceiver convects the gas in the chamber, heat generated by the photoreceiver is transferred to the chamber wall and in turn dissipated to the ambient environment. However, since gas convection has high thermal resistance, the efficiency of its thermal transfer is poor, and therefore is weak in heat dissipation.